We present organic near-infrared photodetectors based on the absorption of charge-transfer (CT) states at the zinc-phthalocyanine–C₆₀ interface. By using a resonant optical cavity device architecture, we achieve a narrowband detection, centered around 1060 nm and well below (>200 nm) the optical gap of the neat materials. We measure transient photocurrent responses at wavelengths of 532 and 1064 nm, exciting dominantly the neat materials or the CT state, respectively, and obtain rise and fall times of a few nanoseconds at short circuit, independent of the excitation wavelength. The current transients are modeled with time-dependent drift-diffusion simulations of electrons and holes which reconstruct the photocurrent signal, including capacitance and series resistance effects. The hole mobility of the donor material is identified as the limiting factor for the high-frequency response. With this knowledge, we demonstrate a new device concept, which balances hole and electron extraction times and achieves a cutoff frequency of 68 MHz upon 1064 nm CT excitation.

中文翻译：

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基于电荷转移吸收的快速有机近红外光电探测器

我们基于在锌酞菁-C ₆₀上电荷转移（CT）态的吸收，介绍了有机近红外光电探测器。界面。通过使用谐振光腔设备架构，我们实现了窄带检测，其中心波长在1060 nm附近，并且远远低于纯材料的光学间隙（大于200 nm）。我们分别在532和1064 nm的波长下测量瞬态光电流响应，分别激发纯材料或CT状态，并在短路时获得几纳秒的上升和下降时间，而与激发波长无关。利用电子和空穴随时间变化的漂移扩散模拟对电流瞬变进行建模，该模拟可重构光电流信号，包括电容和串联电阻效应。供体材料的空穴迁移率被确定为高频响应的限制因素。有了这些知识，我们将展示一种新的设备概念，